buttons and clicks

hi everyone this is a simple qs but it has taken me some time to figure it out but i know twill not stay for long....i have two managing officers who approve some work.either one of them can log in to approve.

i have two buttons...one for PMO and the other for PIC.....project managing officer and project in charge.

i want that when PMO is the one approving and he clicks on his button, the label says Enter pmo password and wen the pic is approving wen he clicks his button, the label changes to enter pic password